US4042963A - Reduction of mechanical stresses on turbosets upon occurrence of three-pole mains short circuits near generators - Google Patents

Reduction of mechanical stresses on turbosets upon occurrence of three-pole mains short circuits near generators Download PDF

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Publication number
US4042963A
US4042963A US05/650,757 US65075776A US4042963A US 4042963 A US4042963 A US 4042963A US 65075776 A US65075776 A US 65075776A US 4042963 A US4042963 A US 4042963A
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United States
Prior art keywords
generator
switch
resistor
mains
short circuit
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Expired - Lifetime
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US05/650,757
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English (en)
Inventor
Karl Kriechbaum
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Licentia Patent Verwaltungs GmbH
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Licentia Patent Verwaltungs GmbH
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/06—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric generators; for synchronous capacitors

Definitions

  • the present invention relates to a method and apparatus for reducing mechanical stresses on the shaft of turbosets and on the generator shaft coupled thereto upon the occurrence of three-pole mains short circuits near the generators and upon the elimination of such short circuits.
  • phase shifted line voltage of the network 8 reappears at the generator and a synchronizing moment is developed. Depending on the mechanical starting conditions at the moment of return of the voltage, this moment leads to transient mechanical oscillations at relatively high amplitude.
  • the above-mentioned publication proposes that the short circuit not be simultaneously switched in all three poles but to initially switch off only one pole.
  • the three-pole short circuit would be converted to a two-pole short circuit and thereafter, with an offset of a defined period of time, the other two poles would be switched off. This will considerably reduce the mechanical stresses.
  • the mechanical stresses still lie above the stresses for which the shaft was designed.
  • a generator switch is connected between the output of the generator and the mains, and a resistor, whose size is adapted to the normal load on the generator, is connected in parallel with the generator switch.
  • the generator switch is opened and thus switches the resistor into the load circuit of the generator.
  • the resistor is bridged, i.e., short circuited, again.
  • the FIGURE is a schematic diagram of an arrangement according to the invention.
  • an electrical generator 1 whose shaft is coupled to the output shaft of a set of turbines 11.
  • the electrical output of generator 1 is connected via a transformer 5 and circuit breakers 6 and 7 to a network 8.
  • a generator switch 3 having a resistor 2 in parallel therewith is connected between the electrical output of the generator 1 and the primary of the transformer 5.
  • a switch 4 which serves to protect the resistor 2 against overloads, is connected in series with the switch 3, which is preferably a very fast-acting switch which opens when a short circuit occurs.
  • switch 3 a very fast acting circuitbreaker as described in the U.S. Pat. No. 3,604,871 can be used.
  • the resistor 2 is, as illustrated, preferably a variable resistor and is dimensioned so that it corresponds to the normal load resistance on the generator before the occurrence of a short circuit.
  • the very fastacting generator switch 3 which has the resistor 2 connected in parallel therewith, is opened, causing the resistor 2 to be switched into the load circuit of the generator 1. Since this resistor 2 is dimensioned so that it corresponds to the load resistance on the generator 1 before the occurrence of a short circuit in the mains, the dangerous effect of the short circuit, when seen from the generator 1, is eliminated.
  • the generator 1 will not be accelerated by the turbine 11 and thus the phase angle between generator 1 and network 8 will not spread.
  • the short circuit can be selectively interrupted by the breaker 6 and a second, not shown breaker in the network 8. This, however, would reduce the load on the generator 1 and the generator 1 would be accelerated by the turboset 11. This is prevented by again closing the generator switch 3 and thus bridging the parallel resistor 2. This then reinstates the original conditions.
  • the mechanical stresses on the shafts of the turboset 11 and the generator 1 in such a case will not exceed the stresses of a two-pole short circuit.
  • the parallel resistor 2 may be a stepping resistor whose size in each case is adapted to the respective load state of the generator 1. It is possible to make do with but a single resistance value if, for example, a resistor is provided whose resistance corresponds to 80% of the load resistance value on the generator 1 and the arrangement 12 according to the present invention, becomes effective only if a certain load is exceeded.
  • Bridging of the resistor 2 upon removal of a short circuit can also be effected, instead of by means of closing the generator switch 3, by a separate circuit closer 9 connected in parallel with the generator switch 3.
  • the generator switch 3 acts quickly so that vibrations of the generator shaft under the influence of the short circuit are prevented if possible. This has the result that no special requirements regarding speed have to be met by the circuit breakers 6 and 7 on the high voltage side, they can be actuated or tripped at three poles and the stresses on the shaft which develop are independent of the moment of actuation.
  • the switch 4 connected in series with the generator switch 3 and the parallel resistor 2 serves to selectively interrupt the resistor current. With this additional switch 4 the resistor 2 can be protected against overloads in case the circuit breaker on the high voltage side does not act in time or a short circuit occurs between the arrangement 12 and the circuit breakers 6,7.
  • the present invention achieves a reduction in stresses not only for the case of the three-pole short circuit but also for faulty synchronizations and for two-pole short circuits in the case where the generator switch 3 is a very fast-acting switch, i.e., a single period switch.
  • a control device 13 is foreseen. This device is connected to the switches 3,4,6,7,9, to the variable resistor 2, and to the current-transformers 14,15,16. If a generator-near fault occurs on the line between the circuit breakers 6,7 and the network 8, for instance at the point 10, then a short circuit current is measured by the current transformers 14,15,16. The signals of the current transformers are led to the control device 13, which causes the operation of the switches in the predescribed way.
  • the resistor 2 is adjusted by the control device 13 in dependance of the load current measured by the current transformer 14.
  • control device 13 an over current relay as described in "Technische Mitteilungen AEG-TELEFUNKEN, 59 (1969) S. 388 - 392" can be used.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Eletrric Generators (AREA)
  • Emergency Protection Circuit Devices (AREA)
US05/650,757 1975-01-25 1976-01-20 Reduction of mechanical stresses on turbosets upon occurrence of three-pole mains short circuits near generators Expired - Lifetime US4042963A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2503034A DE2503034C3 (de) 1975-01-25 1975-01-25 Verfahren zur Verminderung der mechanischen Beanspruchung von Turbosätzen bei generatornahen dreipoligen Netzkurzschlüssen
DT2503034 1975-01-25

Publications (1)

Publication Number Publication Date
US4042963A true US4042963A (en) 1977-08-16

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ID=5937296

Family Applications (1)

Application Number Title Priority Date Filing Date
US05/650,757 Expired - Lifetime US4042963A (en) 1975-01-25 1976-01-20 Reduction of mechanical stresses on turbosets upon occurrence of three-pole mains short circuits near generators

Country Status (7)

Country Link
US (1) US4042963A (US06256357-20010703-M00001.png)
CH (1) CH607398A5 (US06256357-20010703-M00001.png)
DE (1) DE2503034C3 (US06256357-20010703-M00001.png)
FR (1) FR2298889A1 (US06256357-20010703-M00001.png)
GB (1) GB1533931A (US06256357-20010703-M00001.png)
IT (1) IT1054259B (US06256357-20010703-M00001.png)
SE (1) SE406525B (US06256357-20010703-M00001.png)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4148085A (en) * 1976-11-24 1979-04-03 Delle-Alsthom Interconnection circuit-breaker and electric power installation employing same
US4214289A (en) * 1977-05-24 1980-07-22 Fuji Electric Co., Ltd. Stabilizing equipment for power transmission system
US4924342A (en) * 1987-01-27 1990-05-08 Teledyne Inet Low voltage transient current limiting circuit

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2708844C3 (de) * 1977-03-01 1982-04-08 Kraftwerk Union AG, 4330 Mülheim Schutzgerät für eine Generator-Turbineneinheit gegen Überbeanspruchung der Welle

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2316170A (en) * 1937-12-31 1943-04-13 Kesselring Fritz Apparatus for interrupting or controlling electric currents
US3366837A (en) * 1963-08-29 1968-01-30 Philips Corp Surge suppression apparatus for polyphase high voltage system
US3529210A (en) * 1967-02-28 1970-09-15 Mitsubishi Electric Corp Current limiting circuit
US3566152A (en) * 1969-07-23 1971-02-23 Gen Electric High voltage electric circuit breaker including a synchronously closed resistor switch
US3590319A (en) * 1968-07-24 1971-06-29 Bbc Brown Boveri & Cie Apparatus for attenuating voltage surges
US3873887A (en) * 1974-03-18 1975-03-25 Gen Electric Alternating-current power delivery system
US3935509A (en) * 1973-05-21 1976-01-27 Bbc Brown Boveri & Company Limited Synchronized switch with parallel contact

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE442183C (de) * 1921-06-08 1927-03-25 Friedrich Heinemann OElschalter-Schutzschaltung
GB1208124A (en) * 1967-11-02 1970-10-07 Ass Elect Ind Improvements in and relating to a.c. power networks including synchronous dynamoelectric generators and series capacitors

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2316170A (en) * 1937-12-31 1943-04-13 Kesselring Fritz Apparatus for interrupting or controlling electric currents
US3366837A (en) * 1963-08-29 1968-01-30 Philips Corp Surge suppression apparatus for polyphase high voltage system
US3529210A (en) * 1967-02-28 1970-09-15 Mitsubishi Electric Corp Current limiting circuit
US3590319A (en) * 1968-07-24 1971-06-29 Bbc Brown Boveri & Cie Apparatus for attenuating voltage surges
US3566152A (en) * 1969-07-23 1971-02-23 Gen Electric High voltage electric circuit breaker including a synchronously closed resistor switch
US3935509A (en) * 1973-05-21 1976-01-27 Bbc Brown Boveri & Company Limited Synchronized switch with parallel contact
US3873887A (en) * 1974-03-18 1975-03-25 Gen Electric Alternating-current power delivery system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4148085A (en) * 1976-11-24 1979-04-03 Delle-Alsthom Interconnection circuit-breaker and electric power installation employing same
US4214289A (en) * 1977-05-24 1980-07-22 Fuji Electric Co., Ltd. Stabilizing equipment for power transmission system
US4924342A (en) * 1987-01-27 1990-05-08 Teledyne Inet Low voltage transient current limiting circuit

Also Published As

Publication number Publication date
DE2503034A1 (de) 1976-07-29
GB1533931A (en) 1978-11-29
SE7600236L (sv) 1976-07-26
DE2503034B2 (de) 1977-09-15
FR2298889B1 (US06256357-20010703-M00001.png) 1982-03-19
SE406525B (sv) 1979-02-12
DE2503034C3 (de) 1978-05-11
CH607398A5 (US06256357-20010703-M00001.png) 1978-12-15
FR2298889A1 (fr) 1976-08-20
IT1054259B (it) 1981-11-10

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